Structural Defects in InSb Quantum Wells Grown on GaAs (001) Substrates via Al0.09In0.91Sb/GaSb-AlSb Strained Layer Superlattice/AlSb/GaSb Buffer Layers

2005 ◽  
Vol 891 ◽  
Author(s):  
Tetsuya D. Mishima ◽  
Madhavie Edirisooriya ◽  
Michael B. Santos
Keyword(s):  
Quantum Wells ◽  
Buffer Layer ◽  
Defect Density ◽  
Buffer Layers ◽  
Structural Defects ◽  
Tem Analysis ◽  
Cross Sectional ◽  
Plan View ◽  
Strained Layer ◽  
Strained Layer Superlattice

ABSTRACTStructural defects in InSb quantum well (QW) samples have been investigated by transmission electron microscopy (TEM). Using molecular beam epitaxy, an InSb QW with remotely-doped Al0.09In0.91Sb barriers was grown on a GaAs (001) substrate with buffer layers consisting of, in order from the substrate: 1 μm of GaSb, 1 μm of AlSb, 50 nm of GaSb-AlSb strained layer superlattice (SLS), and 3 μm of Al0.09In0.91Sb. Cross-sectional TEM analysis indicates that high densities of threading dislocations (TDs) are created at the two highly lattice-mismatched interfaces, the Al0.09In0.91Sb/GaSb-AlSb SLS and the GaSb/GaAs interfaces. Pairs of stereo images taken from plan-view TEM (PV-TEM) specimens show that TDs propagate through the InSb QW layer. The densities of TDs and micro-twin (MT) defects measured by PV-TEM are 9×108/cm2 and 4×103/cm, respectively. These values are worse than those in an InSb QW layer grown with a different buffer layer by a factor of ∼4. The different buffer layer contains an InSb interlayer that effectively filters out both TDs and MTs. Adopting an interlayer structure and reducing the GaSb and AlSb layer thickness may make it possible to fabricate a lower-defect-density yet thinner InSb QW sample with the type of buffer layer examined in this study.

TEM and SEM Studies of MOCVD-Grown GaP on Si

1985 ◽  
Vol 62 ◽  
Author(s):  
M. M. Ai-Jassim ◽  
J. M. Olson ◽  
K. M. Jones
Keyword(s):  
Defect Density ◽  
Growth Parameters ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Structural Defects ◽  
Organic Chemical ◽  
Cross Sectional ◽  
Plan View ◽  
Si Substrates ◽  
Antiphase Domains

ABSTRACTGaP and GaP/GaAsP epitaxial layers have been grown on Si substrates by metal-organic chemical vapor deposition (MOCVD). These layers were characterized by SEM and TEM plan-view and cross-sectional examination. At growth temperatures ranging from 600° C to 800° C, the initial stages of growth were dominated by three-dimensional nucleation. TEM studies showed that at high temperatures the nuclei were generally misoriented with respect to each other yielding, upon coalescence, polycrystalline layers. The growth of single-crystal layers was achieved by nucleating a 30–50 nm layer of GaP at 500° C, followed by annealing and continued growth at 750 ° C. The defect density in these structures was investigated as a function of various growth parameters and substrate conditions. A high density of structural defects was generated at the Si/GaP interface. The use of 2° off (100) Si substrates resulted in GaP layers free of antiphase domains. These results and their implications are discussed.

Growth of (GaAs)1−x (Si2)x Metastable Alloys using Migration-Enhanced Epitaxy

1991 ◽  
Vol 222 ◽  
Author(s):  
T. Sudersena Rao ◽  
Y. Horikoshi
Keyword(s):  
Buffer Layers ◽  
Double Crystal ◽  
Cross Sectional ◽  
Strained Layer ◽  
Si Substrates ◽  
Migration Enhanced Epitaxy ◽  
Strained Layer Superlattice ◽  
Metastable Alloys ◽  
Si Content ◽  
Strained Layer Superlattices

ABSTRACTEpitaxial (GaAs)1−x (Si2)x metastable alloys have been grown on GaAs (100) substrates using Migration-Enhanced Epitaxy in the composition range of 0<x<0.25. The lattice constant a0 of the alloys was found to decrease with increasing Si content from 0.56543nm at x=0 to 0.5601nm at x=0.25. Double-crystal x-ray diffraction rocking curve measurements and cross-sectional transmission electron microscopy studies made on a 10 period (GaAs)1−x(Si2)x/GaAs strained layer superlattice indicated sharp and abrupt interfaces. High crystalline quality GaAs has been grown on Si substrates using (GaAs)0.80(Si2)0.20/GaAs strained layer superlattices as buffer layers.

Defect Reduction in GaAs Epilayers on Si Substrates Using Strained Layer Superlattices

1987 ◽  
Vol 91 ◽  
Author(s):  
N. El-Masry ◽  
N. Hamaguchi ◽  
J.C.L. Tarn ◽  
N. Karam ◽  
T.P. Humphreys ◽  
...  
Keyword(s):  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Buffer Layers ◽  
Threading Dislocations ◽  
Defect Reduction ◽  
Strained Layer ◽  
Si Substrates ◽  
Density Of Dislocations ◽  
Strained Layer Superlattice ◽  
Strained Layer Superlattices

ABSTRACTInxGa11-xAs-GaAsl-yPy strained layer superlattice buffer layers have been used to reduce threading dislocations in GaAs grown on Si substrates. However, for an initially high density of dislocations, the strained layer superlattice is not an effective filtering system. Consequently, the emergence of dislocations from the SLS propagate upwards into the GaAs epilayer. However, by employing thermal annealing or rapid thermal annealing, the number of dislocation impinging on the SLS can be significantly reduced. Indeed, this treatment greatly enhances the efficiency and usefulness of the SLS in reducing the number of threading dislocations.

Characterization of Gan/Sapphire Interface and the Buffer Layer by TEM/AFM

2001 ◽  
Vol 7 (S2) ◽  
pp. 330-331
Author(s):  
B. Shea ◽  
Q. Sun-Paduano ◽  
D. F. Bliss ◽  
M. C. Callahan ◽  
C. Sung
Keyword(s):  
Buffer Layer ◽  
Gas Flow ◽  
Chemical Vapor ◽  
Wide Band ◽  
Buffer Layers ◽  
Organic Chemical ◽  
Wide Band Gap ◽  
Tem Analysis ◽  
Flow Rates ◽  
Device Applications

Interest in wide band gap III-V nitride semiconductor devices is increasing for optoelectronic and microelectronic device applications. to ensure the highest quality, TEM analysis can characterize the substrate and buffer layer interface. Measurements taken by TEM reveal the density of dislocations/cm2 and the orientation of Burger's vectors. This information allows for changes to be made in deposition rates, temperatures, gas flow rates, and other parameters during the processing.The GaN/sapphire samples grown at AFRL were produced in two consecutive steps, first to provide a thin buffer layer, and the other to grow a lum thick epitaxial film. Both growth steps were prepared using metallic organic chemical vapor deposition (MOCVD) in a vertical reactor. Buffer layers were prepared using a range of temperatures from 525 to 535°C and with a range of flow rates and pressures in order to optimize the nucleation conditions for the epitaxial films.

A Novel Approach for The Production of Low Dislocation Relaxed Sige Material.

1993 ◽  
Vol 319 ◽  
Author(s):  
A.R. Powell ◽  
S.S. Iyer ◽  
F.K. Legoues
Keyword(s):  
Sige Layer ◽  
Silicon On Insulator ◽  
Buffer Layers ◽  
Threading Dislocation ◽  
Tem Analysis ◽  
Cross Sectional ◽  
Novel Approach ◽  
Transmission Electron ◽  
Silicon Thickness ◽  
Buffer Structure

AbstractIn this growth process a new strain relief mechanism operates, whereby the SiGe epitaxial layer relaxes without the generation of threading dislocations within the SiGe layer. This is achieved by depositing SiGe on an ultrathin Silicon On Insulator, SOl, substrate with a superficial silicon thickness less than the SiGe layer thickness. Initially, the thin Si layer is put under tension due to an equalization of the strain between the Si and SiGe layers. Thereafter, the strain created in the thin Si layer relaxes by plastic deformation. Since the dislocations are formed and glide in the thin Si layer, no threading dislocation is ever introduced into the upper SiGe material, which appeared dislocation free to the limit of the cross sectional Transmission Electron Microscopy (TEM) analysis. We thus have a method for producing very low dislocation, relaxed SiGe films with the additional benefit of an SO substrate. This buffer structure is significantly less than a micrometer in thickness and offers distinct advantages over the thick SiGe buffer layers presently in use.

TEM Analysis of Planar Defects in InGaAsN and GaAs Grown on Ge (001) by MOVPE

2016 ◽  
Vol 675-676 ◽  
pp. 639-642
Author(s):  
Pornsiri Wanarattikan ◽  
Sakuntam Sanorpim ◽  
Somyod Denchitcharoen ◽  
Visittapong Yordsri ◽  
Chanchana Thanachayanont ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Buffer Layer ◽  
Growth Direction ◽  
Dark Field ◽  
Tem Analysis ◽  
Cross Sectional ◽  
Planar Defects ◽  
Transmission Electron ◽  
Gaas Buffer Layer ◽  
Field Emission Electron Microscopy

InGaAsN on Ge (001) is proposed to be a part of the InGaP(N)/InGaAs/InGaAsN/Ge four-junction solar cell to increase a conversion efficiency over 40%. In this work, InGaAsN lattice-matched film and GaAs buffer layer grown on Ge (001) substrate by metal organic vapor phase epitaxy (MOVPE) were examined by transmission electron microscopy (TEM). Electron diffraction pattern of InGaAsN taken along the [110]-zone axis illustrates single diffracted spots, which represent a layer with a uniformity of alloy composition. Cross-sectional bright field TEM image showed line contrasts generated at the GaAs/Ge interface and propagated to the InGaAsN layer. Dark field TEM images of the same area showed the presence of boundary-like planar defects lying parallel to the growth direction in the InGaAsN film and GaAs buffer layer but not in the Ge substrate. TEM images with the (002) and (00-2) reflections and the four visible {111} planes reflections illustrated planar defects which are expected to attribute to antiphase boundaries (APBs). Moreover, the results observed from atomic force microscopy (AFM) and field emission electron microscopy (FE-SEM) demonstrated the surface morphology of InGaAsN film with submicron-sized domains, which is a characteristic of the APBs.

Tem Study of GaSb/InAs Strained Layer Supeplattices

1984 ◽  
Vol 37 ◽  
Author(s):  
B. C. De Cooman ◽  
C. B. Carter ◽  
G. W. Wicks ◽  
T. Tanoue
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Defect Structure ◽  
Tem Analysis ◽  
Cross Sectional ◽  
Strained Layers ◽  
Strained Layer ◽  
Zinc Blende ◽  
High Resolution Tem

Cross-sectional TEM of GaSb/InAs superlattices grown by MBE on (100) GaAs and (100) GaSb substrates shows an unusual defect structure within the strained layers. Dislocations are present within the layers and at the interface. High-resolution TEM analysis of the structure of the InAs layers suggests that these layers grow by an island mechanism. A crystal structure different from the zinc blende, is found to be present within the GaSb layers.

Atomic Force Microscopy Study of GaN-Buffer Layers on SiC(0001) By MOCVD

1996 ◽  
Vol 423 ◽  
Author(s):  
Dongsup Lim ◽  
Dongjin Byun ◽  
Gyeungho Kim ◽  
Ok-Hyun Nam ◽  
In-Hoon Choi ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Microscopy Study ◽  
Growth Conditions ◽  
Interfacial Free Energy ◽  
Buffer Layers ◽  
Optimum Growth ◽  
Cross Sectional ◽  
Atomic Force ◽  
Transmission Electron ◽  
Gan Buffer Layer

AbstractBuffer layers promote lateral growth of films due to a decrease in interfacial free energy between the film and substrate, and large 2-dimensional nucleation. Smooth surfaces of thebuffer layers are desired. Optimum conditions for GaN-buffer growth on the vicinal surface of 6H-SiC(0001) were determined by atomic force microscope (AFM). AFM analysis of the GaN nucleation layers led to an optimum growth conditions of the GaN-buffer layer which was confirmed by cross-sectional transmission electron microscopy, Hall measurements and photoluminescence spectra. Optimum growth conditions for GaN-buffer layer on SiC(0001) was determined to be 1 minute growing at 550°C.

Microstructural And Microchemical Analysis of Chalcopyrite Cu(In,Ga)Se2 Films

2003 ◽  
Vol 763 ◽  
Author(s):  
Chun-Ming Li ◽  
Chang-Hui Lei ◽  
Ian M. Robertson ◽  
Angus Rockett
Keyword(s):  
Grain Boundaries ◽  
High Performance ◽  
Structural Defects ◽  
Ion Milling ◽  
Mechanical Grinding ◽  
Cross Sectional ◽  
Plan View ◽  
Microchemical Analysis ◽  
Transmission Electron ◽  
Means Of Transmission

AbstractThe microstructure and microchemistry of Cu(In, Ga)Se2 (CIGS) films have been analyzed by means of transmission electron microscopy (TEM). Specimens were obtained from a number of groups producing high-performance solar cells from these materials. Both plan-view and cross-sectional TEM samples were prepared by mechanical grinding and ion milling. Twins can be found easily within the films while dislocations are present only in a few grains and with low density. No extended structural defects such as stacking faults were discovered. X-ray energy dispersive spectroscopy was used to study the chemical composition of grains and grain boundaries. Experimental results showed no difference between the composition in the grain interiors and the grain boundary. In addition, there is no obvious enhancement of oxygen and sodium at grain boundaries. Structural depth dependences were also not found.

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